The ultraviolet ray emitting element which irradiates ultraviolet rays in the range of the 300-400 nm (for example, the middle wavelength thereof is 365 nm), is used for a treatment for curing or drying an adhesive agent, a paint, ink, a resist, etc. which has sensitivity in this wavelength range, or conversely various treatments, such as a melting treatment, a softening treatment etc. For example, in a light emitting treatment for adhesion of a pickup lens for an optical disc, or adhesion of electronic parts to a substrate etc., it is necessary to irradiate light to a small spot, and in some of ultraviolet ray emitting apparatuses for performing such a treatment, light is irradiated to a fine spot by guiding, for example, ultraviolet rays from a ultraviolet rays light source by a light guiding fiber which is formed by bundling a plurality of optical fibers, or by condensing the ultraviolet rays from an ultraviolet rays light source so as to be a spot shape by a condenser lens.
In the conventional art, as an ultraviolet rays light source in such an ultraviolet ray emitting apparatus, for example, a discharge lamp, such as a xenon lamp or an extra-high pressure mercury lamp, has been used suitably. In recent years, however, an ultraviolet ray emitting apparatus using a light emitting diode element (it is hereafter called a “UV-LED”.) as a light source has been proposed (for example, “Ultraviolet LED of 100 mW light output whose light emission wavelength is the same as that of a mercury lamp”, Nikkei electronics, Oct. 21, 2002, and p. 28.) with developments of the light emitting diode element using light emitting material which can emit ultraviolet rays with a high output (for example, Japanese Laid Open Patent (Tokkai) No. 2005-015764).
In general, when a light emitting diode element (LED element) is used as a light source, in order to use light from an LED element efficiently, an LED element package is formed, for example, by integrating (packaging) such an LED element and a condenser lens or a structure component with a condensing action (for example, Japanese Laid Open Patent No. (Tokkai) 2001-196644 and Japanese Laid Open Patent (Tokuhyo) No. 2002-543594). Hereafter, with reference to FIG. 1, as disclosed in patent documents 2, the structure of an LED element package of Japanese Laid Open Patent No. (Tokkai) 2001-196644 is explained.
FIG. 7 is a schematic cross sectional view of the structure of a conventional LED element package. In FIG. 7, an LED element 51 emits light by supplying electric power, and this LED element 51 is arranged in a concave portion of a container 52 made of a liquid crystal polymer etc. Lead electrodes 53 and 54 which are connected to electrodes 51A and 51B of the LED element 51 respectively are provided on the container 52. Specifically, the lead electrodes 53 and 54 are exposed to the outside, at the bottom of the concave portion of the container 52, and are electrically connected to the electrodes 51A and 51B of the LED element 51 which is arranged in the container 52. The electrodes 51A and 51B of the LED element 51 may be connected to the respective lead electrodes 53 and 54 by, for example, a joining method using a wire bonding of gold wire, or a joining method using electric joint material, such as silver paste. The LED element 51 is sealed (molded) with translucency resin 55 which transmits light emitted from the LED element 51, so that protection against oxidation of the LED element 51 and protection from the outside thereof is provided. In this LED element package 50, the side face(s) of the concave portion of the container 52 has a light reflection face (slop) so as to spread toward the outside thereof. Furthermore, the outer surface (contour) of the translucent resin 55 is formed in convex shape, so that, due to the convex lens effect of the translucent resin 55, the condensing nature of the light emitted from the LED element 51 increases, and the light extraction efficiency of the LED element package 50 can be improved.
Moreover, an LED light emitting element package disclosed in Japanese Laid Open Patent No. Tokuhyo 2002-543594 has the structure in which a lens is provided independently. As shown in FIG. 1 or 2 of the Japanese Laid Open Patent, the LED element is molded with transparent resin material containing a converter for wavelength conversion, which is made of an epoxy resin. Further the condenser lens is provided on the transparent resin material, and the condenser lens is joined and fixed by the transparent resin material so as to be integrally formed therewith.
And, when carrying out packaging of the UV-LED element which emits ultraviolet rays, the above package structure (resin mold structure) cannot be used. Namely, the conventional translucent resin material used in order to mold the LED element in the above-mentioned package structure, deteriorates when ultraviolet rays (light with a wavelength of 380 nm or less) are irradiated thereon, so that the ultraviolet rays transmittance thereof gradually decreases with use, for example, becoming below a half thereof, and a stable ultraviolet ray output cannot be secured. Therefore, the packaging cannot be carried out by molding the UV-LED element with the conventional transparent resin material.
Japanese Laid Open Patent (Tokkaihei) No. 10-233532 discloses that, in order to solve the problem, while, for example, gas such as nitrogen etc. which ultraviolet rays tend to transmit is enclosed in a space where a UV-LED element which emits light including ultraviolet rays is arranged, a lens is made from quartz glass etc. having ultraviolet rays transparency, so that packaging of the UV-LED element is carried out.